National Hellenic Research Foundation

Athens, Greece

National Hellenic Research Foundation

Athens, Greece

The National Hellenic Research Foundation is a historic and scientific research center in Athens, Greece, Wikipedia.

Time filter

Source Type

Karousis N.,National Hellenic Research Foundation | Tagmatarchis N.,National Hellenic Research Foundation
Chemical Reviews | Year: 2010

The unique morphology and structure of carbon nanotubes (CNT) keep attracting a great number of researchers to explore the novel properties of these materials. Among various surface functionalization techniques, oxidation of CNTs is probably the most widely studied. Early treatment techniques involved gas-phase oxidation in air and oxidative plasmas. Carboxylated CNTs were extensively used as precursors for further covalent modification of CNTs, through esterification and/or amidation reactions. Moreover, a few other direct esterification/amidation procedures of oxidized CNTs were reported. In one of them, acid purified SWCNTs were treated with molten urea, which functions both as solvent and as reactant. Modification of CNTs with ionic liquids is expected to improve their compatibility and stability, enhancing the potential of CNTs in applications such as sensors and actuators, by improving the electrical contact with media.

Gonos E.S.,National Hellenic Research Foundation
Advances in Experimental Medicine and Biology | Year: 2010

Homeostasis is a key feature of cellular lifespan. Maintenance of cellular homeostasis influences the rate of aging and its efficiency is determined by the cooperation between protein stability and resistance to stress, protein refolding, protein repair and proteolysis of damaged proteins. Protein degradation is predominately catalyzed by the proteasome which isresponsible for cell clearance of abnormal, denatured or in general damaged proteins as well as for the regulated degradation of short-lived proteins. Impaired proteasome function has been tightly correlated to aging both in vivo and in vitro and thus, emphasis has been given recently in identifying ways of its activation. A number of studies have shown that the proteasome can be activated by genetic manipulations as well as by factors that affect either its conformation and tability or the expression of its subunits and the rate of proteasome assembly. This "readjustment" has been shown to have a great impact on retention of cellular homeostasis since it promotes lifespan extension. This chapter focuses on protein homeostasis and its direct link to proteasome function, dysfunction and manipulation and provides insights regarding the activation of proteasome-mediated protein degradation that, in turn, ensures health maintenance. ©2010 Landes Bioscience and Springer Science+Business Media.

Economopoulos S.P.,National Hellenic Research Foundation | Tagmatarchis N.,National Hellenic Research Foundation
Chemistry - A European Journal | Year: 2013

Graphene is turning out to be the material that will effectively kick-start a new era for nanotechnology. The impressive properties of this atom-thick carbon layer are taking shape and form with early reports of successful applications based on it. The turning point for this material will be its low-cost mass production. In this report a chemist's perspective on the production methods for graphene and the subsequent functionalization processes is discussed. The key for graphene's widespread adoption is its facile and cost-effective mass production. For material scientists, it is also important to chemically modify it, thus enriching its properties. A summary of the most widely-used exfoliation and covalent functionalization methods on the road from graphite flakes to graphene hybrid materials is presented (see figure). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oikonomou E.,National Hellenic Research Foundation | Pintzas A.,National Hellenic Research Foundation
BioFactors | Year: 2013

Despite the significant advances in clinical research, surgical resection, radiotherapy and chemotherapy are still used as the primary method for cancer treatment. As compared to conventional therapies that often induce systemic toxicity and eventually contribute to tumor resistance, the TNF-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that selectively triggers apoptosis in various cancer cells by interacting with its proapoptotic receptors DR4 and KILLER/DR5, while sparing the normal surrounding tissue. The intensive studies of TRAIL signaling pathways over the past decade have provided clues for understanding the molecular mechanisms of TRAIL-induced apoptosis in carcinogenesis and identified an array of therapeutic responses elicited by TRAIL and its receptor agonists. Analysis of its activity at the molecular level has shown that TRAIL improves survival either as monotherapies or combinatorial therapies with other mediators of apoptosis or anticancer chemotherapy. Combinatorial treatments amplify the activities of anticancer agents and widen the therapeutic window by overcoming tumor resistance to apoptosis and driving cancer cells to self-destruction. Although TRAIL sensitivity varies widely depending on the cell type, nontransformed cells are largely resistant to death mediated by TRAIL Death Receptors (DRs). Genetic alterations in cancer can contribute in tumor progression and often play an important role in evasion of apoptosis by tumor cells. Remarkably, RAS, MYC and HER2 oncogenes have been shown to sensitise tumor cells to TRAIL induced cell death. Here, we summarise the cross-talk of oncogenic and apoptotic pathways and how they can be exploited toward efficient combinatorial therapeutic protocols. © 2013 International Union of Biochemistry and Molecular Biology, Inc.

Pispas S.,National Hellenic Research Foundation
Soft Matter | Year: 2011

Vesicular structures composed of different components are attracting significant attention from the soft matter community both in terms of basic understanding of such complex assemblies of amphiphiles and in view of potential nanotechnological applications. In this article current developments in research concerning mixed vesicular structures assembled through interactions between synthetic block copolymers and low molecular weight surfactants are highlighted. Some future directions and perspectives for further advancement in the field are also discussed. © 2011 The Royal Society of Chemistry.

The self-assembled nanostructures formed in mixed solutions of a double hydrophilic anionic-neutral block copolymer, poly[(2-sulfamate-3-carboxylate) isoprene-b-ethylene oxide] (SCIEO), and the vesicle-forming surfactant, didodecyldimethylammonium bromide (DDAB), are investigated. In these solutions electrostatic interactions exist between the anionic poly[(2-sulfamate-3- carboxylate)isoprene] block and the cationic surfactant. Combined static and dynamic light scattering measurements indicate that at low copolymer concentration vesicles of DDAB with adsorbed block copolymer chains are present in the solutions. As block copolymer concentration increases the structure of the nanoassemblies transforms to a core-shell, micellar-like structure, with a poly(ethylene oxide) corona and a core formed by the complex of poly[(2-sulfamate-3-carboxylate)isoprene] chains and DDAB molecules. This transformation of global aggregate structure should be attributed to a collapse of the DDAB vesicle bilayer as the number of complexed surfactant head groups to anionic polymeric segments increases. This happens in order to satisfy the conformational requirements of the complexing polymeric block and the steric requirements in the PEO corona, which apparently overcome the existing interactions between surfactant molecules in the ordered bilayer of initial DDAB vesicles. Block copolymer decorated vesicles show lower stability to an increase in solution temperature compared to micellar-like aggregates. Both nanostructures are found to be stable to changes in solution ionic strength, due to the combination of electrostatic and hydrophobic interactions acting within the mixed aggregates. © 2011 The Royal Society of Chemistry.

Kyrtopoulos S.A.,National Hellenic Research Foundation
Environmental and Molecular Mutagenesis | Year: 2013

Although experience from the application of OMICS technologies in population-based environmental health studies is still relatively limited, the accumulated evidence shows that it can allow the identification of features (genes, proteins, and metabolites), or sets of such features, which are targeted by particular exposures or correlate with disease risk. Such features or profiles can therefore serve as biomarkers of exposure or disease risk. Blood-based OMIC profiles appear to reflect to some extent events occurring in target tissues and are associated with toxicity or disease and therefore have the potential to facilitate the elucidation of exposure-disease relationships. Further progress in this direction requires better understanding of the significance of exposure-induced network perturbations for disease initiation and progression and the development of a framework that combines agnostic searches with the utilization of prior knowledge, taking account of particular elements which characterize the structure and evolution of complex systems and brings in principles of systems biology. Environ. Mol. Mutagen. 54:468-479, 2013. © 2013 Wiley Periodicals, Inc.

Koufaki M.,National Hellenic Research Foundation
Expert Opinion on Therapeutic Patents | Year: 2014

Introduction: Lipoic acid (LA), a naturally occurring 1,2-dithiolane analog that plays an essential role in mitochondrial bioenergetic reactions, has gained unprecedented attention as nutritional supplement and as therapeutic agent. Moreover, LA conjugates with other pharmacophores represent a promising approach toward the development of multifunctional drugs. Areas covered: The reviewed patent applications from January 2011 to April 2014 include combinations of LA with other bioactive compounds as well as LA conjugates for the treatment of a wide range of clinical conditions. Additionally, some patents disclose methods to overcome the stability problems of LA. Expert opinion: LA is currently in clinical use for the treatment of diabetic neuropathy, while small clinical trials using combinations of LA with known bioactive agents have been undertaken. The use of the LA is hampered by its instability and its rapid metabolism. Thus, formulations containing LA, in a form ensuring its stability and improving its bioavailability, can have important applications as medicines, nutritional supplements or cosmeceuticals. LA hybrids with other pharmacophores endowed with various activities, possess an enormous potential to promote human health and have been the subject of numerous publications and patent applications. Nevertheless, reliable in vivo data and clinical trials are necessary to prove these beneficial effects. © 2014 Informa UK, Ltd.

Lathiotakis N.N.,National Hellenic Research Foundation
International Journal of Quantum Chemistry | Year: 2013

In reduced density matrix functional theory, approximate total energy expressions in terms of the one-body reduced density matrix (1RDM) are minimized under the appropriate N-representability subsidiary conditions. The optimal 1RDM is in general nonidempotent. Measures of nonidempotency are the total charge of weakly occupied states and correlation entropy given in terms of the eigenvalues of the 1RDM. In this work, we calculate these quantities for several systems using different 1RDM functionals and compare with accurate results from a multideterminant method. Our goal is to assess 1RDM functionals with respect to the quality of the obtained 1RDM. © 2012 Wiley Periodicals, Inc.

Kapeta S.,National Hellenic Research Foundation | Chondrogianni N.,National Hellenic Research Foundation | Gonos E.S.,National Hellenic Research Foundation
Journal of Biological Chemistry | Year: 2010

Replicative senescence in human fibroblasts is accompanied with alterations of various biological processes, including the impaired function of the proteasome. The proteasome is responsible for the removal of both normal and damaged proteins. Due to its latter function, proteasome is also considered a representative secondary antioxidant cellular mechanism. Nrf2 is a basic transcription factor responsible for the regulation of the cellular antioxidant response that has also been shown to regulate several proteasome subunits in mice. We have established in this study the proteasome-related function of Nrf2 in human fibroblasts undergoing replicative senescence. We demonstrate that Nrf2 has a declined function in senescence, whereas its silencing leads to premature senescence. However, upon its activation by a novel Nrf2 inducer, elevated levels of proteasome activity and content are recorded only in cell lines possessing a functional Nrf2. Moreover, treatment by the Nrf2 inducer results in the enhanced survival of cells following oxidative stress, whereas continuous treatment leads to lifespan extension of human fibroblasts. Importantly the Nrf2-proteasome axis is functional in terminally senescent cultures as these cells retain their responsiveness to the Nrf2 stimuli. In conclusion, these findings open up new directions for future manipulation of the senescence phenotype. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.

Loading National Hellenic Research Foundation collaborators
Loading National Hellenic Research Foundation collaborators